Cinematographic film stretching



Jan. 4 1927. 1,613,300

L. T. TROLAND CINEMATOGRAPHIC FILM, STRETCHING 2 Filed lzpril 25, 1925 2Sheets-Sheet 1 five 70307 jeonardl. 270227212 Jan. 4 1927.

L. T. TROLAND CINEMATOGRAPHIC FILM STRETCHING I 2 Sheets-Sheet 2 jjrz/ven/torx L e 0 7 ZQ TLZ ZTT'OZd/i 2d periods of use printed films.Cupping,

Patented Jan. 4,1927.

1 UNITED STATES PATENT (OFFICE.

SSAGHUSETTS, ASSIGNOR, BY MESNE AS- PICTURE CORPORATION, OF BOSTON, MAS-cmnmaroe mrmc FILM srnnrcnme.

Application filed. April 25, 1925. Serial No. 25,916.

This invention relates to the treatment of cinematographic film stripsand involves film stretching to eifect a general elongation or toproduce variable elongations of films in proportion to variableshrinkage throughout the length thereof.

Amongthe many causes of film shrinkage may be mentioned the following byway of example; In the commercial working of the imbibition process itis found that the matrix has a tendency to shrink and that after theprinting of a number of blanks, generally less than the number which itis desired to print in the ordinary operation of the imbibition process,a general shrinkage of such extent occurs that the matrix is apt to bedestroyed, due to tearing of the sprocket holes during registration witha normal blank, unless the matrix is stretched. Also during storage ofmatrices for periods of substantial length between their shrinkagefrequently occurs. The positive blanks used in the imbibition process,if punched by inaccurate perforating machinery may also need to bestretched to render them uniform throughout their lengths prior to use.There are also-ttwo conditions which occur under certain" circumstanceswhich also render film strip stretching necessary in the case of acondition in which the edges perforated by the sprocket holes areshorter than the image carrying portion intermediate the sprocket holes,may

necessitate stretching to overcome the condition. Under othercircumstances grapevining results, that is, the edge portions oi the-strip are longer than the image bearing portion.

Among the objects of the present invention is the provision of a methodof treatment which will overcomethe difiiculties mentioned and whichwillprovide for .more than a mere transitory improvement in thecondition of the film treated. Another object is the provision ofapparatus for carrying out the method in which a long film strip may betreated in a continuous process, in which accurate results may beproduced, in which the process may a chamber through be carried outsubstantially automatically, and in which care may be taken of changingor different conditions of the film strips under treatment.

In one aspect the invention comprises film feeding and winding means,which may be provided by the same or different toothed members, andmeans cooperating with said feeding and winding means for stretching (afilm strip beyond its elastic limit to effect a relatively permanentchange in condition thereof. The elastic limitmay be reduced byappropriately heating the film if desired and the film may beretained'under tension until cooling takes place. The stretching may beefiected by means for lengthening the path of film travel between thefeeding and winding m'eans a predetermined amount, or by means providingan adjustable tension upon the portion undergoing stretching. Undercertain conditions means may be provided to tension the edges more thanthe middle of. the, strip and under other conditions resort may be hadto a reverse arrangement. To heat the strip a heater may be arranged in'which the strip passes while under tension, or heated air may besupplied to such a chamber to render plastic the film strip passingtherethrough.

The humidity of the heating medium is of much less importance than thetemperature, but reasonably dry air of" approximately humidity isdesirable.

For the purpose of illustrating the invention one embodiment and amodification are. disclosed in the accompanying drawings, in which:

Fig. 1 is a side view;

Fig. 2 is a section on Fig. 1; v

Fig. 3 is a fragmentary view on an enlarged scale of a portion of thestructure disclosed in Fig. 2;

Fig'. 4 is a vertical HofFig.2;and

Fig. 5 .is a somewhat diagrammatic view. of a modified'form of theinvention.

the line 2-2 of section on the line In the apparatus illustrated inFigs. 1" to E 4 of the drawings, 1 represents a. casing or more doors 2having glass plates therein through which conditions inside the casingmay be observed. The interior of the casing is divided into two chambers37 and'38 by a transversely extending partition 39 having an opening orslot 40 therethrough. Mounted upon the exterior of the casing arebrackets 4, 5, 6, and 7. Bracket 4 supports a journal 8 upon which asupply reel 9 is rotatable. Bracket 5 supports a take-up reel 10receiving the stretched strip upon completion of the process. Bracket 6supports a motor 11 which drives a positive feeding. and winding, ortraction mechanism, generally designated 12, which is mounted on thebracket 7. Mechanism 12 comprises a shaft 13 which through a wormcoaxial therewith drives a worm wheel 14 upon a shaft 15. The shaft 13carries a pulley 16 which is driven by a belt 17 from the motor 11, andshaft 15 carries a driving pulley 18 connected by a belt 19 to a pulley20 which is coaxial with the take-up'reel 10. The' pulley 20 isconnected through a suitable friction mechanism 21 with the take-up reel10, the friction vconnection permitting the slippage necessary as thequantity of film upon the reel'increases.

The shaft 12 is journalled instandards 22 and carries thereon a toothedmember 23 whose construction will shortly .be described. A rectangularframe 24 having side elements spaced apart by a distance slightlygreater than the width of the member 23 is mounted on the bracket 7 insuch position that a plane contacting with the sides of the member 24toward the member 23 is substantially tangent to the periphery of thelatter. Suported for rotation on parallel axes in the rame 24, inpositions substantially equidis-' tant above andbelow the horizontalplane including the axis of rotation of the member 23, are guide rolls27 and 28. Pivotally supporte by the top ofthe frame 24- is a member 29U-sha 'd in cross section and carrying a pair 0 rolls 30 and 31 1ying inthe same vertical planes transverse to the axis of the member 23 as thelatter and approximately equi-d-istant from the vertical plane includingthe axis of the member23. The rolls 30-and 31 have grooves 30' and 31'into which the sprocket teeth extend. Spring means 32 presses the member29, together with the rolls 30 and 31, toward the surface of the member23. Y

The member 23 has a cylindrical eriphera-l surface 34 and around thissurfiice extend two rows-of tapered pins 35. These pins maybe held inlace. in an desired manner and are pre erably liar ened by singing andtapered,'the pins of one row being adapted to fit the sprocket holes-inthe film strip exactly, both longitudinal'and transversely of the filmstrip, while the others may preferably fit the sprocket longitudinally,but not transversely, thereby affording clearance to take care ofshrinkage or expansion transversely of the strip.

An opening 41 is"formed in the wall of the chamber 37 ata point justabove thepartition 39 and an opening is formed in the wall of thechamber 38 at a point just below the partition 39. The openings 41 and42 fall just above and just below the horizontal plane which includesthe axis of the member 23 and within the chamber 37 and 38 are guiderolls 44 and 45 so positioned that portions of the film strip tangentialto the member 23 and to they rolls 44 and 45 will pass through theopenings 41 and 42 without touching the casing.

Adjacent the top of the chamber 37 a roll cylindrical, concave or crown-peri -heries. In each case the rolls are preferab y provided withflanges 52 spaced apart so as to receive approximately exactly betweenthem a film strip of standard width. 'All the other rolls mentioned are'also provided with flanges to uide the film strips properly thereover.lpon the brackets 7 a roll 53 is provided to guide the film strip as itpasses downward to the take-up reel 10.. 'To render the film stripplastic and lower its yield ppint the portion of the film within thecham er 37 is warmed, preferably to a temperature of about 160 F. andfor this purpose heated air of average humidity is supplied to thechamber 37 through a pipe 54. The chamber 38-may be cooled if desired bythe-supply of cold air thereto but it is ordinarily suflicient if atemperature not much above atmos heric is maintained in this chamber,and to facilitate this avent 55 is provided topermitany heatedairpsecuring access to the chamber through the opening 40 to escape.

As may best be observed from Fig. 2 a film strip M is drawn from thesupply reel 9 downwards under the roll 27 and then over the top of themember 23 in contact with whose periphery the strip i held by the rolls30 and 31, the engagement of the pins 35 with the sprocket holes of thestrip positively drawing the film at a definite rate. 'From the member23 the strip passes under the roll 44, thence upward, making half a turnbefore it reaches the roll 47, over the top of that roll, and thendownward through the slot 40 and beneath the roll 49 rolls 47 and 49 maybe provided with truly.

lit

V jected to is wound. The strip M is wound with its image carrying-orprinting surface outermost upon the reel 9, and accordingly the onlymember with which this surface of the strip contacts at any time duringits wholeperiod of travel from the supply to the takeup reels is themember 23, and as this member has a highly polished surface and assliding relative to the surface is absolutely'preeluded by theengagement of the pins 35 upon the member 23 with the sprocket holes inthe film strip there can be no damage to the strip through scratching orabrasion.

As the strip enters the chamber 37 it is subthe heating action of theair therein and, at a temperature ofabout 160 F., it becomessemi-plastic and its yield point is substantially lowered so that aweight of but a few pounds is suificient to stretch the film str1p thenecessary amount. As each portion of the strip undergoes warming .undertension as it passes through chamber 37 all parts of the strip will beapproximately equally elongated and the weight 51 is adjusted topreclude over-stretching while providing. for stretching to thenecessary degree. crown surfaces the central portions of the film stripswill be tensioned more than the edges and accordingly will stretch to athat it sets in its stretched condition,

' through greater extent. Film strips in which grape- Vining has takenplace may ,therefore be brought to a condition in which the edges of thefilm strip will be no longer than the central or image-bearing portion.If cupping has occurred, concave rolls may be used, and as this willthrow the major tension upon the lateral edges of the film strips thecondition of cupping will be overcome. If, as in the case of matrices,the film strip has simply shortened generally the elongation necessaryto permit the safe use of the matrix for further printing will beeffected by cylindrical rolls. As the film strip passes through thechamber 38 for a substantial distance before it again reaches the member23 it is given an opportunity to cool sufiiciently so the period ofsetting before leaving this chamber being.determined by the distance thestrip, is caused to travel therein.

Fig. 5 shows diagrammatically a modified construction. In this form ofthe invention, the film strip M passes from a supply reel (not shown)downwardly over a toothed paying-out member 60, thence upwardly awarming chamber 61, over a If the rolls 47 and 49 are made with bodilyadjustable roll 62, and downward and under awinding or tensiontoothed-member 63 from which 'it passes off and is wound up by a windingor take-up reel not shown. The structure of the members 60 and 63correspond closely to that of the member 23 previously described. Eachof these members 60 and 63 has a cylindrical surface provided withspaced annular rows of hardened sprocket teeth adapted to fit into thesprocket holes of a film strip to be stretched. Coaxial with-the members60 and 63 and rotating respectively therewith are bevel gear members 64and 65 which mesh respectively with beveled gear members 66 and 67carried upon a rotatable shaft 68. This mechanism provides equalperipheral speeds for the members 60 and 63. The members 60 and 62 aresuitably driven by power.

The roll or pulley 62 which is preferably provided with lateral flanges69 may have its surface 70 cylindrical, or be made either in the form ofa crown pulley or a concave,

pulley depending upon the result which the stretching is designed toaccomplish. This pulley is journalled and the latter is in turn carriedby a vertically adjustable rod 72 which passes through a bushing 73supported in a frame 74 which also supports the members 60 and 63. A nut75'co-operates with the threaded 7 2 and is adjustable upper end 7 2 ofthe rod to effect bodily adjustment of the roll 62 in a directionperpendicular to the plane 1ncluding the axes of the members 60 and 63.v

The nut and screw construction may be a micrometer arrangement and thelength of the film strip between the point of tangency with the adjacentsides of the members 60. and 63 may be exactly adjusted to apredetermined length, say a given number of standard sprocket holespaces or slightly longer to compensate for slight contraction after thestretching. As a result a film strip subjected to the action of thismechanism will be brought to an exactly. standard form.-

ln general this mechanism, save that the paying-out and windlng-inmeans-are sepain a yoke member 71 rate from each other instead of beingcom bined in a single member 'as in the first means and that the lengthof path between the paying-out and winding-in means is adjustablypredetermined instead of being subject to possible variation, is similarto the mechanism illustrated in Figs. 1 to 4, although of coursemechanical details are substantially. different and cooling in this formwill be observed to take place in the open ,air.

While this application discloses-one speclfic embodiment of theapparatus constructed in accordance with the invention and well adaptedto the practice of the inventive process and also a modified form ofmechamsm, it is to be understood that various of which said strapstretched film strip to set it in stretchedcondition.

3. The method of treating cinematographic film strips which includes thesteps of rendering a film strip plastic, stretching the same whileplastic, and setting the stretched film while under tension.

4. The methotl of treating cinematographic film strips which includesthe steps of heat ing a film strip to render it plastic, stretchingthesamc while plartic, and cooling the stretched film to set it while itis-still under tension.

The method of treating cinematographic film strips which include? thesteps of mudering a film st rip plastic, longitudlnally tensioning saidfilm strip while plastic under" tension unequally applied transverselythere of, and cooling the stretched film strip to set it.

6. The method of treating cinematographic film strips which includes thesteps of heating a film stripto render it plastic, longitudinallytnsioning said film strip while --plastic under tension unequallyapplied transversely thereof, and cooling the stretched film to set itwhile still under tension. I

7. The. method. of stretching cinematographic filmstrips which includesthe-steps of placing under tension an extended length of film strip,heating a portion of said tensioned length to 'a degree to render itplastic, thereby elongating the film,,and subsequent- 1y cooling saidheated portion While still under tension.

8. The method of stretching cinematographic film strips which includesthe steps of successively passing a continuous strip through a heatedchamber and through. a cooling chamber during transit through each isunder tension.

9. The metho of stretching cinematographic film strips which includesthe steps of successively subjecting the portions of a continuous filmstrip to heatto a degree to render it plastic an to a lower temperatureto set it, and imposing a tension upon said strip during its subjectionto such different temperatures.

10. The method of stretching ciaflnato graphic film-strips whichincludes the steps of tensioning a relatively long portion of a filmstrip and first heating the same to an extent to renderit'p'lastic' andthereafter cooling the same to set it.

11. The method of treating cinematographic film stripswhich includes thestep zones of such a strip. 1

12. The method of treating cinematographic film strips which includesthe step of tensioning different lateral zones of a strip in inverseproportion to their excesses of length over normal. v 13. Apparatus forthe treatment of cinematographic .film strips including in combinationfilm feeding and traction means adapted to simultaneously operate upondifferent portions of a film strip to provide equal movement thereof,means for controllable tensioning the film strip between the feeding andtraction means, and means for controlling the temperatures of the stripbetween the feeding and traction means so as to render the filmsufiiciently plastic in. one portion to cause stretching thereof andthere-' after to sufli'ciently cool the same to set the film in thestretched condition.

.of unequally tensioning different lateral,

14. Apparatus for the treatment of einematographic film stripsincluding, in combination, a film feeding and traction means adapted tosimultaneously operate upon two portions of a film strip to provideequal movement thereof, means for heating a portion of film between thesaid feeding and traction means to render it plastic, and means forapplying tension to the heated portion of film to stretch the same.

15. Apparatus for the treatment of cinematographic film stripsincluding,-in combination, a film feeding and traction meansadapted tosimultaneously operate upon two portions of a film. strip to provideequal movement of :the vsaid port-ions, means for heating a portion ofthe film strip between the said feeding and traction means, means forapplying tension to the said portion while in the heated condition to'stretch the same and means for cooling the said film portion whileunder tension to attain a permanent set thereof.

16. Apparatus for the treatment of cinematographic film stripsincluding, in com-- bination, film feeding and traction means, and meansfor stretching a film strip and setting it in stretched conditionc0-operating with said feeding and winding means and including means forlowering the yield point of said strip during stretching.

17. Apparatus for the treatment of einematographic film stripsincluding, in combination. a rotatable member carrying upon itsperiphery means engageable in the sprocket holes of a film strip, meansfor' guiding spaced partitions of a film strip inspaced portions toengagement with spaced and means for stretching the portion of said filmstrip intermediate said spaced portions.

18. Apparatus for the treatment of cinematographic film stripsincluding, in combination, a rotatable member carrying up on itsperiphery means engageable in the sprocket holes of a film strip, meansfor guiding spaced portions of a film strip into engagement with spacedportions of the periphery of said member, andmeans for heating andstretching the portion of said film strip intermediate said spacedportlons.

19. Apparatus for the treatment of cinematographic film stripsincluding, in combination, a rotatable member carrying upon itsperiphery means engageable in the sprocket holes of a film strip, meansfor guiding of a film strip into engagement with spaced portions of theperiphery of said member, and means for heating. stretching, and coolingthe portion of said film'strip intermediate said spaced portions.

20. Apparatus for the treatment of cine.- matographic strips including,in combination, a rotatable member carrying upon its periphery meansengageable in the sprocket holes of' a film strip, means for effectingrotation thereof, means for guiding and maintaining spaced portions of afilm strip in engagement with spaced portions of the pe riphery of saidmember, and means including a roll engageable with the portions of saidstrip intermediate said spaced portions and adjustable relative to saidrotatable member for applying a film strip stretching tension to saidportion.

21. Apparatus for the treatment of cinematographic film stripsincluding, in com'-' bination, a rotatable member carrying upon itsperiphery means engageable in the' Sprocket holes of a film strip, meansfor ef-' fecting rotation thereof, means for guiding spaced portions ofa film strip into engagement with spaced portions of the periphery ofsaid member whereby said member pays out at one of said portions andwinds in at the other, and means for treating the portion of a filmstrip between said spaced portions thereof including a heating chamberand a cooling chamber traversed by said strip, and means for tensioningthe portion of said strip in said chambers.

22. Apparatus for thetreatment of'cinematographie film strips including,in combi-- nation, a rotatable member carrying upon its periphery means-'engageable in the sprocket holes of a film strippmeans for effectingrotation thereof, means for guiding spaced portions of a film-strip intoengage ment with spaced portions of the periphery of said member wherebysaid member pays out at one of said portions and winds in at the other,and means for treating the portion of a film strip between said spacedp01 tions thereof including a heating chamber and a chilling chambertraversed by said strip, and means for adj ustably tensioning theportion of said strip in said chambers.

23. Apparatus for-the treatment of cinematographic film stripsincluding, in combination, a rotatable member carrying upon itsperiphery means engageable in the sprocket holes of a film strip, meansfor effecting rotation thereof, means for guiding spaced portions of afilm strip into engagement with spaced portions of the-periphery of saidmember whereby said member pays out at one of saidportions and Winds inat the other, and means for treating the por tion of a filmvstripbetween said spaced portions thereof including aligned heating andsetting chambers, afilm guiding pulley rota'table on a fixed axis in oneof said chambers, and a film tensioning pulley rotatable on a movableaxis in the 0ther.

24. Apparatus for the treatment of cinematographic film stripsincluding, in combination, a rotatable member carrying upon itsperiphery means engageable in the sprocket holes of a film strip, meansfor effectin rotation thereof, means for guiding spaced portions of afilm strip into engagement with spaced portions of the periphery of saidmember whereby said member pays out at one of said portions and winds inat the other, and means for treating the portion of a film strip betweensaid spaced portions movable axis on the other and means for exerting ayielding tension on said last mentioned pulley.

25. Apparatus for the treatment of-cinematographic film stripsincluding, in combination, rotatable means for paying out and winding inspaced portions of a film strip, and means for treating a loopintermediate said portions including a pulley for subjects ing said loopto tension having a strip engaging periphery whose elements -arecurvilinear.

26. Apparatus for stretching shrunken cinematographic film to standardlength comprising positively interconnected means engaging the sprocketholes of the film at points spaced along the path of the film apredetermined constant distance suflicient to stretch the portion of theshrunken film therebetween to standard length as it is fed past saidmeans.

27. Apparatus for cinematographic film to standard length comprisingpositively interconnected means engaging the sprocket holes of the filmat points spaced along the path of the film, and means forpredeterminedly effecting variastretching a shrunken tion in the lengthof film between said points of engagement, said points of engagementbeing spaced appropriately to stretch the portlon of the shrunken filmto standard length as it is fed past saidmeans.

28. Apparatus for stretching a shrunken cinematographio film 'tostandard length comprising positively interconnected means engaging thesprocket holes of the-film at 10 points spaced along the path of thefilm a predetermined distance suflicient to stretch the portion ofshrunken film therebetween to standard length as it is fed past saidmeans, and means co-operating With the portion of said film between saidpositively interconnected means to vary predeterminedly the lengththereof.

Signed by me at Boston, Massachusetts, this 14th day of April 1925.

LEQNARD T. TROLAND.

